Right around the corner from the Hilton Garden Inn Hotel (where most of you will be staying) is the Blue Hills Reservation! If you park at the Trailside Museum (or even walk from the hotel to the museum), you can follow the trail up to Eliot Tower to see a gorgeous view of the Boston skyline over the fall foliage! Would recommend this activity to ages 4+, unless you've got a super agile toddler.
For those under 4, the Trailside Museum itself has some little critters and fun, educational exhibits! Caroline loved coming here as a little kid.
Trillium is a fun brewery pretty much across the street from the Hilton Garden Inn Hotel (where most of you will be staying)! Good drinks, good lawn games, good vibes all around.
Topgolf is a fun spot for groups of any age--golf, drinks, and food! We HIGHLY recommend booking a reservation if you are interested in checking it out--while it's less than 10 minutes away from the Hilton Garden Inn Hotel (where most of you will be staying), it is known to have obscene wait times if you don't have a reservation!
The commuter rail goes directly into Boston from the Route 128 station, which is a 5-minute drive from the Hilton Garden Inn Hotel (where most of you will be staying). The website linked has the schedule of trains. To get into the city, you will take a train going toward South Station. To leave the city and return to Route 128 station, you can take any of the following trains from South Station: Providence, Stoughton, or Wickford Junction. We highly recommend using Google Maps to make sure you're riding the right train!